The treatment of disease via the inhibition of growth factors, their receptors and the regulatory systems associated with them is an established therapy concept. That cancers adapt to these treatments, or express mutant receptors that are not bound by standard ligands means that it is advantageous to treat cancer patients with a variety of such inhibitors in order to broaden spectrum and maintain inhibition of tumour growth.
Epidermal growth factor is an example of a growth regulator that is disregulated in certain diseases such as lung cancer and amyloid related dementias.
Various inhibitors of this growth factor and its receptors are known and have utility in treating certain forms of cancer, albeit limited to those that express specific mutant forms of the target. Clearly, in the context of a variable tumour, a substance that inhibits multiple mutant forms of this target would be preferable to an agent that inhibits specifically only one mutation. Similarly, although tumours may express a mutant form of growth factor receptor, they may also express or over-express multiple growth factor receptors that together confer the capacity for over-growth. A compound that exerts inhibition of multiple receptors is, therefore, more generally or widely applicable than one that inhibits only one receptor type.
While inhibition of growth stimulation is a desirable goal in cancer therapy, elimination of the tumour itself requires either a substance that causes tumour cells to die, or one that promotes immune action on the tumour.
One means of achieving this objective is to select molecules that are ligands to the key signaling proteins of tumours that suppress local immune response. It is known, for example, that preventing tumours or their stromal cells from secreting IL-10 is an effective means of activating Natural Killer and T-cells in the tumour environment. A ligand of moderate potency to a MAP kinase can have this effect.
Similarly, many tumours are dependant on hormone related signaling. Inhibition of hormone signal processing is a valid means of suppressing growth or inducing apoptosis. Androgen processing in particular is a potent factor in prostate cancer. Androgen processing receptor kinases are, therefore, also relevant cancer targets.